Vessel ballast water discharges are a major source of nonindigenous species introductions to marine, estuarine, and freshwater ecosystems of the United States. Ballast water discharges are regulated by EPA under authority of the Clean Water Act (CWA) and the U.S. Coast Guard under authority of the Nonindigenous Aquatic Nuisance Prevention and Control Act, as amended (NANPCA).
Under the authority of the CWA, EPA’s Vessel General Permit requires the flushing and exchange of ballast water by vessels in Pacific-near-shore voyages and the saltwater flushing of ballast water tanks that are empty or contain only un-pumpable residual ballast water. While useful in reducing the presence of potentially invasive organisms in ballast water, ballast water exchange and saltwater flushing can have variable effectiveness and may not always be feasible due to vessel safety concerns.
EPA's Office of Water has requested SAB review of technical documents and available data on the efficacy of ballast water treatment systems and advice on improving the performance of such systems.